Solenoids are well known in the art and are often utilized as a means for moving a component a predetermined distance at a predetermined time. In its most basic form, a solenoid is an electro-mechanical device which converts electrical energy into linear or rotary motion. Current passes through a coil of insulated copper wire producing a magnetic field which moves a ferro-magnetic plunger located within the core of the coil. Steel parts surround the coil to contain the flux path for maximum pull, push or rotational force. A typical solenoid comprises a steel frame or shell which surrounds the coil of wire and directs the flux path. The coil, when energized, creates the magnetic lines of force. A plunger, located within the coil, reacts to the magnetic pull and moves to the center of the coil against a stop or pole piece.
A solenoid can be utilized to open a valve, activate a switch, apply a brake, or a number of other activities where mechanical movement is required and only an electrical energy source is available or practical.
A typical solenoid structure includes movable components as well as non-movable or stationary components. The stationary components include a bottom plate, a housing, a tube having a coil assembly, and a top plate. A pole piece may be attached to the bottom plate. A movable plunger assembly is located within the tube. A rod is attached to one end of the plunger. The rod transfers the mechanical movement of the plunger to the device requiring the movement.
When an electrical current is applied to the coil assembly, the plunger moves quickly in a predetermined direction toward a stop or pole piece. The pole piece provides a stop for the plunger movement. However, when the plunger and stop strike each other at the end of the stroke, a loud noise is produced. As the size of the solenoid increases, so does the level of noise produced.
It is an object of this invention to provide a solenoid assembly having sound dampened characteristics to produce substantially quiet operation. It is another object to provide a method of dampening unwanted sound from solenoids that are already in use in the field.
These and other objects of the present invention will become evident in the following descriptions. The inventors know of no prior art that teaches or discloses their invention.